Method of joining pulpboard



Aug, 26, 3924, 1505,5339

D. M. SUTHERLANQ, JR

METHOD OF JOINING PULPBOARD Filed Oct. '7 1919 WITNESSES 11v l/EA/TOR fi 17/4/1054 /1 50mm AM we Br Patented Aug. 26, 1924.

UNITED STATES PATENT OFFICE.

DANIEL MANSON SU'IHERLAND, an, or TRENTON, NEW JERSEY, ASSIGNOR 'ro THE AGASOTE mnmaoann 00., or EWING TOWNSHIP, MERCER COUNTY, NEW JERSEY,

A. CORPORATION OF NEW JERSEY.

m 'rnon or comma runrnoann.

Application filed October 7, 1819. Serial No. 829,128.

To all whom it may concern:

Be it known that I, DANIEL MANSON SUTHERLAND, Jr., a subject of the King of Great Britain, and a resident of Trenton, Mercer County, State of New Jersey, have invented a certain new and useful Improvement in Methods of Joining Pulp board, of which the following is a speclfication.

My invention relates to a method of making a joined article of pulp board, and to the product of such method, and such method comprises, broadly speaking, the application of a cementing substance to two p eces to be joined while such pieces are still in a spongy condition, that is to say, have not yet been subjected to the final pressing operation, and then compresslng said two pleces. This method is of particular utility when used to join pieces of pulp board containing a large admixture, preferably 50% or more, by weight, of mineral pitch, asphalt, or llke substances.

Pulp board is usually made by running paper pulp wood pulp or the like lnto a mold, and, by means of pressure, removmg the majority of the water (see for lnstance \patent to Daniel M. Sutherland, and myself, No. 971,936, dated October 4:, 1910, and patent to myself, No. 1,272,566, dated July 16,1918) and subsequently drying out the remainder of the water by the application of heat, preferably in a suitably constructed drier. The board, after substantially all the water has been removed, is in what I term a spongy condition, and is then subjected to heat and pressure to form a compact board.

The pieces or portions of spon pulp board to be joined may be of any desired slze or configuration. They may consist for instance of two sheets of pulp board, or two small pieces of waste, or scrap-board which it is desired to convert into a larger sheet, or they may form portions of one piece of pulp board, for instance two edge portions of a sheet bent to meet at two edges to form a tubular structure.

Preferably, if the joint is to be made edge to edge, the two pieces or portions to be joined are each given a chamfer edge either during the primary formation of such pieces or portions in a suitable mold, or by tooling the sheets after they have been formed in the nsual mold, and subjected to the usual prenot be desired to have the thickness of the joint uniform with, that of the remainder of the pieces or portions, any other suitable form of joint may be employed, for instance alap oint, or a butt joint covered by a third piece, or strip, cemented over the meeting line of the two pieces to be joined.

My invention is, however, not limited to the joining of two pieces ed e to ed e, as the two pieces may be oined side to sife, by bemg superimposed in whole or in part, so that two pieces of smaller thickness may be united into a structure of greater thickness. It is obvious that a great many forms of joint may be constructed with the aid of my invention, as practically any form of joint which can be constructed with wood and glue can be duplicated with pulp material with the aid of my invention. Of course, it ma be necessary to modify the form of one or oth of the plates of the hotpress to correspond to the form which the joined article is to take.

' The cements which I have found most suitable for my method are those made from the phenol resins, with or without the addition of other binders. I may, however, use any other suitable cement, for instance one containing blood-albumen-casein. en ll speak in my claims of a cement I refer, of course, to a cement suitable for this purpose.

After the cement has been ap lied the two pieces or. portions are subjecte for a suitable length of time to the combined influence of heat and pressure applied preferably by means of a heated press. The degree of heat and of pressure will'have to be determined, and can readily be determined, in each instance, with reierence to the thickness and nature of the material, and the degree of compactness desired in the finished article. For example, if two pieces of pulp board, each containing 50% by weight of mineral pitch and each one-half inch in thickness, while in their spongy condition, are to be joined by a scarf joint, they may becompressed for from three to five utes under a pressure of 160 pounds to the square inch,

. and the will be found to have been reduced to,a thickness of about one-quarter of an inch. The degree of heat employed must be suflicient to soften the pitch in the board, If a more compact, or thinner, product be desired the pressure may be increased to 250 pounds per square inch, and the resulting product will then have a thickness of about three-sixteenths of an inch. If two pieces of board, containing no pitch, or other er, and each one-half inch in thickness while in their spongy condition, are to be a scarf joint, they may be comjoined b pressed or from three to five minutes under a; pressure of 160 pounds to the square inch, and at a temperature of 300 F., and they will-then be found to have been reduced to a thickness of about one-quarter of an inch. Of course, if no binder is added to the pulp before the same is formed into a board, a binder should be added, preferably after the completion of the compression, so as to hold the fibres in their compressed condition. China wood oil may,-for instance, be used for'that purpose.

It is, of course, preferable in most in-- stances, if not in all, to apply heat and pressure to the joint simultaneously with the application of heat and pressure to the remaining portions of the piece or pieces Whose edges are to be joined, so that the heating and compressing of the porti ons forming the joint may form a part of the usual operation of heating and compressing the article. In any event the formation of the joint does not necessitate the employment I of any greater, or appreciably greater,

amount of heat and pressure than that otherwise necessary for the compacting .of the pulp board, as the pressure necessary for compacting the material serves also to form the joint.

By my method I therefore avoid the necessity of roviding a separate operation, and of emp oying additional heat and pressure, for the formation of the joint, which necessity would be present if I first compacted my side, the sha ed portion j, 70, Z, m representing the sheet after compacting and joining, the uncompacted pieces being indicated by f, g, h, 2'. The line a, 6, indicates the'chamfered edges of the two uncompacted portions, and the line 0, (Z, represents the approximate plane of the finished joint. This illustration of joint and press is, of course, illustrative only, and represents only one of mlang ways in which my invention can be app 1e I do not claim as new the broad method of joining two articles by cement and pressure, whether the joint is made with scarfed edges, or in any other form, as I am well aware that this idea is old in many arts, for instance in the art of wood working. I believe, however, that I am the first to unite two pieces of unfinished, that is, still spongy, pulp board, by placing a suitable cement upon the spongy mass, and then applying heat and pressure to compact the material to final: form and at the same time to bring about the formation of a joint; thus not 0 1y forming the joint without any more, or appreciably more, heat and pressure than would be necessary for the compacting of the pulp board, but also producing a joined article in which the cement has entered the material and which is, therefore, much stronger than an article formed of two pieces of paper pulp cemented after final compression.

I claim:

1. In the art of makin ulp board that improvement which inc u es overlapping two edges of portions of substantially uncompressed spon and therefore incomplete, pulp boar applying a layer of a suitable cement between said two edges and then subjecting such edges to the action of a hot press so as to provide both heat and pressure sufiicient materially to decrease the thickness of, and thus to compact, such portions into completed pulp board while simultaneously joining such portions.

2. In the art of making pulp board that improvement which includes overlapping two edges of portions of substantially uncompressed spongy, and therefore incomplete, pulp board having a. suitable binder incorporated therein, applying a layer of a suitable cement between said two edges and then subjecting such edges to the action of a hot press so as to provide both heat and p-ressuresufiicient materially to decrease the thickness of, and thus to compact, such portions into completed pulp board while simultaneously joining such portions.

3. In'the art of making pulp board that "improvement which includes overlapping .two edges of portions of substantially uncompressed spongy, and therefore incomplete, pulp oardhavin approximately 50% of asphaltic material incorporated therein, applyin 'a layer of a suitable cement between said two edges and then subjecting such edges to the action of a hot press so as to provide both heat and pressure sufiicient materially to decrease the thickness memos of, and thus to compact, such portions into completed pulp board while simultaneously joining such ortions.

4. A joine article of pulp board comprising two portions of compressed pulp board containing a binder united at their edges and a layer of cement located between, and attached to each of, the same, said article having been formed by applying a suitable cement to the edges of said portions while in substantially uncompressed spongy condition and then subjecting such edges to the action of a hot press so as iJOPIOVIdB both heat and pressure siiflicient materially to decrease the thiche'ss of, and thus to com- 15 act, such portions into completed pul card While simultaneously joining sue portions.

In testimony whereof I have hereunto set my hand.

DANIEL HANSON SUTHERLAND, Jr. 

